JP2023142443A - electrolyte analyzer - Google Patents

Abstract

To provide an electrolyte analyzer capable of easily determining the type or concentration of interfering ions.SOLUTION: The electrolyte analyzer having an ion-selective electrode that uses the potential measurement includes: a storage unit that stores the relationship of potential changes over time with respect to interfering ions; and an interfering ion analysis unit that detects the effects of interfering ions based on the potential change over time obtained from the ion-selective electrode while a sample is still in solution after the sample comes into contact with the ion-selective electrode.SELECTED DRAWING: Figure 5

Description

The present invention relates to an electrolyte analyzer.

In an electrolyte concentration analyzer that performs analysis by potentiometric measurement, the potential generated at the solid-liquid interface between the ion-sensitive membrane of the ion-selective electrode (ion electrode) and the sample liquid (analyte) is obtained and converted into concentration. This is what I am analyzing. The potential generated at the solid-liquid interface between the ion-sensitive membrane and the sample liquid changes depending on the activity of the ion to be measured in the sample liquid (Nernst response). Due to the ease of measurement, ion-selective electrodes are used to analyze electrolyte concentrations in liquid samples such as food, industrial water/wastewater, and biological samples. When acquiring the potential, the sample solution is brought into contact with the ion-sensitive membrane of the electrode, and the measurement is performed when the potential becomes stable.

Usually, an ion-selective electrode measures one specific type of ion, and the same number of electrodes are required to detect multiple types of ions. Further, the ion-selective electrode is preferably an electrode with enhanced ion selectivity so as to be less susceptible to the influence of ions other than the ions to be measured. However, it is technically difficult to improve the ion selectivity of anion-selective electrodes, and they are more susceptible to interfering ions than cation-selective electrodes.

An example of an electrolyte concentration measuring device installed in an automatic biochemical analyzer will be explained. Since the specimen to be analyzed is a biological sample such as serum, the ion species and ion concentration in the specimen are determined to some extent, and it is required to analyze relatively small differences in ion concentration with high throughput. The three types of electrolyte items commonly used in biochemical analysis are Na, K, and Cl ions.

Regarding cations such as Na ions and K ions, ion-sensitive membranes having high ion selectivity are known and are not easily affected by interfering ions. On the other hand, it is technically difficult to create an ion-sensitive membrane that is not susceptible to both hydrophilic ions and lipophilic ions using an anion-selective electrode such as Cl ions. Therefore, analysis accuracy is improved by devising measurement methods.

For example, there is a method of calibrating using a matrix of standard conditions for specimens containing interfering ions. However, even with this method, in the case of a sample containing interfering ions of a concentration or type different from normal, the influence of the interfering ions cannot be canceled, which may affect the ion concentration analysis results. Examples include lyophilized control serum (low bicarbonate ion (HCO ₃ ⁻ ) concentration), and patient specimens receiving drugs containing ions not normally present.

Technologies such as those disclosed in Patent Documents 1 to 3 have been disclosed as techniques that can cope with specimens in which the types and concentrations of interfering ions are irregular.

In Patent Document 1, "In addition to the base electrode, which is a chloride ion selective electrode, there is a first auxiliary electrode that has a higher selectivity coefficient for lipophilic ions than the base electrode, and a second auxiliary electrode that has a higher selectivity coefficient for hydrophilic ions than the base electrode. A technique is disclosed in which an auxiliary electrode is provided, and if the value measured by the auxiliary electrode is larger than the value measured by the base electrode and the difference exceeds a set value, an alarm is generated.

Additionally, US Pat. Known ion concentration and known ion interference between the ion and other ions in the liquid detected at one of the electrodes and/or electrode interference between the electrodes using a neural network algorithm Compensating for the ionic interference and/or the electrode interference based on the results of a comparison of training data indicating the concentration.

In Patent Document 3, "The concentration of target ions contained in the sample is calculated using the result of calculating the selection coefficient of the ion-selective electrode and the result of measuring the concentration of coexisting ions contained in the sample." A technology has been disclosed.

Japanese Patent Application Publication No. 2000-121595 US Patent Application Publication No. 2013/0304395 International Publication No. WO2019/163281 pamphlet

A problem with conventional techniques is that it is difficult to determine the type or concentration of interfering ions. For example, the techniques disclosed in Patent Documents 1 and 2 require measurement values from a plurality of electrodes with different selectivities. Further, for example, in Patent Document 3, it is necessary to determine the interfering ion concentration using another analysis method.

The present invention was made to solve such problems, and one object thereof is to provide an electrolyte analyzer that can more easily determine the type or concentration of interfering ions.

Another object of the present invention is to provide an electrolyte analyzer that can make such a determination using one electrode.

An example of the electrolyte analyzer according to the present invention is
In an electrolyte analyzer that has an ion-selective electrode and uses potential measurement,
It has a memory section that stores the relationship of potential changes over time with respect to interfering ions,
After the sample comes into contact with the ion-selective electrode, the sample includes an interfering ion analysis unit that detects the influence of the interfering ions based on a potential change over time obtained from the ion-selective electrode while the sample is still. It is characterized by

The electrolyte analyzer according to the present invention can more easily determine the type or concentration of interfering ions. Also, according to one example, one electrode can make such a determination.

1 is a block diagram showing the overall configuration of a flow type electrolyte concentration measuring device according to Example 1 of the present invention. 3 is a flowchart when starting up the device according to the first embodiment of the present invention. 3 is a flowchart during electrolyte concentration analysis according to Example 1 of the present invention. FIG. 3 is a diagram showing a typical potential waveform according to Example 1 of the present invention. FIG. 3 is a diagram showing potential waveforms when various liquids are measured according to Example 1 of the present invention. FIG. 2 is a schematic diagram showing the phenomenon mechanism used in the present invention. FIG. 2 is a block diagram of an experimental device for verifying the principle of the present invention. FIG. 3 is a diagram showing the results of an experiment using an experimental device for verifying the principle of the present invention. FIG. 2 is a schematic diagram showing the phenomenon mechanism used in the present invention. It is a flowchart at the time of electrolyte concentration analysis based on Example 2 of this invention. It is a flowchart at the time of electrolyte concentration analysis based on Example 3 of this invention.

The present inventors conducted research and development on a method for detecting and reducing the influence of interfering ions in an electrolyte concentration measuring device in order to achieve more reliable analysis. As a result, they found that it is possible to more easily detect interfering ions (for example, without installing additional electrodes or sensors), which has been difficult in the past. Furthermore, by utilizing information on these interfering ions, we have created a device that can perform more stable analysis.

Embodiments of the present invention will be described below with reference to the drawings.
[Example 1]
FIG. 1 is a schematic diagram showing an example of a flow type electrolyte concentration measuring device according to Example 1 of the present invention. The electrolyte concentration measurement device 100 is an electrolyte analysis device that has an ion-selective electrode and uses potential measurement. The feature of this embodiment is particularly in the measurement results of the Cl ion electrode in which the ions to be measured by the electrolyte concentration measuring device 100 are anions, and it is possible to detect ions interfering with anions.

The device of this example is a device that analyzes the concentration of three types of ions, Na, K, and Cl ions, and together with the analysis results of each ion concentration, it also analyzes whether or not the Cl ion concentration measurement was affected by interfering ions. The determination result is output.

Note that the counter ion to the fixed charge in the sensitive membrane is called the main ion (Cl ion in the case of a Cl ion electrode). are called interfering ions.

The electrolyte concentration measurement device 100 includes a measurement section 170, a potential measurement section 171, a concentration calculation section 172, an output section 174, a device control section 175, an input section 176, an interfering ion analysis section 181, and a storage section 182.

The measurement unit 170 includes three types of electrodes as ion-selective electrodes: a Cl ion electrode 101 (chloride ion electrode), a K ion electrode 102 (potassium ion electrode), and a Na ion electrode 103 (sodium ion electrode). Further, a comparison electrode 104 is provided. The sensitive membrane of the Cl ion electrode 101 is an ion sensitive membrane based on an anion exchange membrane having a high density of fixed charges.

In this example, the ion selective electrode is a flow type ion selective electrode. It is preferable to use a flow type ion-selective electrode because it is easy to measure potential changes immediately after the liquid comes to rest.

Inside the dilution tank 110, there is a diluted sample in which a sample dispensed from a sample nozzle (not shown) and a diluent dispensed from a diluent supply nozzle 108 are mixed together, or an internal standard solution supply nozzle. The internal standard solution dispensed from 109 is temporarily stored. The sipper nozzle 107 descends into the dilution tank 110, and the diluted specimen or internal standard solution in the dilution tank 110 is transferred to the ion-selective electrodes (Cl ion electrode 101, K ion electrode 102, and Na ion electrode 103) using the sipper syringe 133. (the same applies below). Further, a comparison electrode solution is introduced from a comparison electrode solution bottle 161 into the flow path of the comparison electrode 104 using a sipper syringe. During this time, the vacuum suction nozzle 106 descends to suck out the diluted sample or internal standard solution remaining in the dilution tank 110 and discharge it into the waste liquid tank 111. A vacuum pump 112 is connected to the waste liquid tank 111.

Here, the detailed operation of the mechanical part when introducing the liquid into the flow path of the electrode will be described. First, when introducing the liquid in the dilution tank into the flow path of the ion-selective electrode, close the solenoid valves 121 and 125, open the pinch valve 105 and solenoid valve 122, and insert the sipper nozzle 107 into the dilution tank 110. and pull the sipper syringe 133. Next, when introducing the reference electrode solution into the flow path of the reference electrode 104, the solenoid valve 121 is opened, the pinch valve 105 is closed, and the sipper syringe 133 is pulled, so that the reference electrode solution is introduced from the reference electrode solution bottle 161. It is introduced into the flow path of the electrode 104. Further, in order to discharge the liquid accumulated in the sipper syringe, the solenoid valve 122 is closed, the solenoid valve 125 is opened, and the sipper syringe 133 is pushed.

Further, a solenoid valve 123, a solenoid valve 124, a solenoid valve 126, a solenoid valve 127, and a syringe pump 131 for internal standard solution are provided.

The reference electrode solution introduced into the flow path of the reference electrode 104 and the solution introduced into the ion-selective electrode come into contact at the liquid junction 120, and the ion-selective electrode and the reference electrode 104 are electrically connected through the liquid. The state will be as follows. At this time, the electromotive force (potential) between the comparison electrode 104 and each ion-selective electrode changes depending on the concentration of the ion to be measured in the liquid introduced into the flow path of the ion-selective electrode.

Potential information during these series of analysis operations is acquired by the potential measuring section 171. The interfering ion analysis section 181 receives from the potential measuring section 171 the potential waveform when the liquid is stationary after introducing the liquid into the flow path of the ion-selective electrode, and uses the information stored in the storage section 182 to analyze the interfering ions. Analyze the impact of

The concentration calculation unit 172 receives a measured potential at a stable timing suitable for concentration calculation from the potential measurement unit 171, and calculates the concentration of the ion to be measured.

The output unit 174 displays the operating status of the device received from the device control unit 175 and the analysis results from the concentration calculation unit 172 and the interfering ion analysis unit 181. From the input section 176, the operator can input sample information, various parameters, device operation instructions, and the like. Details of the calculation method will be described later.

Next, the flow when starting up the electrolyte concentration measuring device 100 will be explained using FIG. First, the startup procedure will be explained. The electrolyte concentration measuring device 100 is started up (S201), electrodes are installed (S202), and reagent bottles are installed (S203). Prime the reagent to replace and fill the syringe pump and flow path with new reagent (S204). The internal standard solution is continuously measured to confirm that the potential of the electrode is stable (S205). In order to obtain a calibration curve for each ion-selective electrode, two types of standard solutions with known concentrations are measured and the slope is calculated (S206). Subsequently, the internal standard solution concentration is calculated (S207).

Here, specific operations in S206 and S207 will be explained. After dispensing a known low concentration standard solution into the dilution tank 110 using a dispensing nozzle (not shown), the diluent in the diluent bottle 151 is dispensed into the dilution tank using the diluent syringe pump 132, and the settings are made. Dilute the known low concentration standard solution at the ratio D. The diluted known low concentration standard solution in the dilution tank 110 is sucked through the sipper nozzle 107 and introduced into the flow path of each ion-selective electrode.

Thereafter, a reference electrode solution is introduced into the flow path of the reference electrode 104 from inside the reference electrode solution bottle 161. At the liquid junction, the reference electrode solution and the diluted known low concentration standard solution come into contact. Immediately after the diluted standard solution is introduced into the electrode channel and while the solution is stationary, each electromotive force between each ion-selective electrode and the comparison electrode 104 is measured by the potential measurement unit 171.

In the meantime, the liquid remaining in the dilution tank 110 is sucked up by the vacuum suction nozzle 106, and then the internal standard solution in the internal standard solution bottle 141 is dispensed into the dilution tank 110. The internal standard solution in the dilution tank 110 is sucked through the sipper nozzle 107 to fill the channel of each ion-selective electrode with the internal standard solution, and the reference electrode solution is introduced from the reference electrode solution bottle 161 into the channel of the reference electrode 104. do.

The electromotive force of each electrode is measured by the potential measurement unit 171 immediately after the internal standard solution is introduced into the electrode channel and while the solution is stationary. In addition, in the meantime, after sucking up the liquid remaining in the dilution tank 110 with a vacuum suction nozzle, and dispensing a known high concentration standard solution into the dilution tank 110 with a dispensing nozzle (not shown), the syringe pump for the dilution liquid is used. 132 is used to dispense the diluent in the diluent bottle 151 into a dilution tank, and dilute the known high concentration standard solution at a set ratio D.

The diluted standard solution of known high concentration in the dilution tank is sucked through the sipper nozzle and introduced into the flow path of each ion-selective electrode. Thereafter, a reference electrode solution is introduced into the flow path of the reference electrode 104 from inside the reference electrode solution bottle 161. At the liquid junction, the reference electrode solution and the diluted standard solution of known high concentration come into contact.

Immediately after the diluted standard solution is introduced into the electrode channel and while the solution is stationary, each electromotive force between each ion-selective electrode and the comparison electrode 104 is measured by the potential measurement unit 171. In the meantime, the liquid remaining in the dilution tank 110 is sucked up by the vacuum suction nozzle, and then the internal standard solution in the internal standard solution bottle 141 is dispensed into the dilution tank 110. The internal standard solution in the dilution tank is sucked through the sipper nozzle to fill the channel of each ion-selective electrode with the internal standard solution, and the reference electrode solution is introduced into the channel of the comparison electrode 104 from inside the reference electrode solution bottle 161.

The electromotive force of each electrode is measured by the potential measurement unit 171 immediately after the internal standard solution is introduced into the electrode channel and while the solution is stationary. Further, the liquid remaining in the dilution tank 110 is sucked up by a vacuum suction nozzle.

As described above, the potential measurement unit 171 obtains potential waveforms of the three types of liquids, the low concentration standard solution, the high concentration standard solution, and the internal standard solution, immediately after introduction and while the liquids are stationary. The concentration calculating section 172 receives the potential value (potential difference) in the time domain where the potential is most stable from among the potential waveforms obtained by the potential measuring section 171, and uses it as the measured electromotive force (EMF) of each liquid. Note that according to the above sequence, the waveform of the internal standard solution is obtained twice, but the liquids have the same composition and, in principle, the same value can be obtained. If the same value cannot be obtained, it may be due to the remaining liquid from the previous measurement. The information may be used to correct the slope sensitivity and internal standard solution concentration. It can also be used as an alarm for the device status or as an indicator for the timing of device maintenance.

The concentration calculation unit 172 calculates the slope sensitivity SL corresponding to the calibration curve from the electromotive force received from the potential measurement unit 171 using the following equation (1).
(A) Slope sensitivity SL=(EMF _H - EMF _L )/(LogC _H -LogC _L )...Equation (1)

However, SL: Slope sensitivity EMF _H : Measured electromotive force of known high concentration standard solution EMF _L : Measured electromotive force of known low concentration standard solution C _H : Known concentration value of high concentration standard solution _CL : Known concentration of low concentration standard solution value

The above operation is called calibration. Note that the slope sensitivity SL corresponds to the "2.303×(RT/zF)" part of the Nernst equation below.
Nernst equation: E=E0+2.303×(RT/zF)×log(f×C)
(E0: constant potential determined by the measurement system, z: valence of the ion to be measured, F: Faraday constant, R: gas constant, T: absolute temperature, f: activity coefficient, C: ion concentration)

The slope sensitivity SL can be calculated from the temperature and the valence of the ion to be measured, but in order to further improve the analytical accuracy, in this example, the slope sensitivity SL unique to the electrode is determined by the above-mentioned calibration.

Next, the internal standard solution concentration is calculated from the slope sensitivity and the electromotive force of the internal standard solution.
(B) Internal standard solution concentration C _IS = C _L ×10 ^a ... Formula (2)
a=(EMF _IS -EMF _L )/SL... Formula (3)

However, _CIS : Internal standard solution concentration EMF _IS : Internal standard solution electromotive force

A specific example of a calibration method has been described above, but regardless of this procedure, a different procedure may be used as long as two or more types of liquids having different ion concentrations can be introduced into the flow path and the electromotive force can be measured. Note that the above standard solution may contain interfering ions such as bicarbonate ions. Alternatively, a standard sample having a composition similar to a serum sample or urine sample may be measured and further calibration correction may be performed.

After calibration, analysis is performed using samples such as serum or urine. Next, the flow during continuous analysis in this example will be explained using FIG. 3.

Specifically, when the measurement operation is started (S301), the internal standard solution in the internal standard solution bottle 141 is dispensed into the dilution tank. The internal standard solution in the dilution tank is sucked through the sipper nozzle 107 to fill the channel of each ion-selective electrode with the internal standard solution, and the reference electrode solution is introduced into the channel of the comparison electrode 104 from inside the reference electrode solution bottle 161. (S302).

The electromotive force of each electrode is measured by the potential measurement unit 171 immediately after the internal standard solution is introduced into the electrode channel and while the solution is stationary (S303). In the meantime, after sucking up the liquid remaining in the dilution tank 110 with a vacuum suction nozzle, the sample is dispensed into the dilution tank 110 with a dispensing nozzle (not shown), and then diluted using the diluent syringe pump 132. The diluent in the liquid bottle 151 is dispensed into a dilution tank, and the sample is diluted at the set ratio D.

The diluted specimen (sample) in the dilution tank 110 is sucked through the sipper nozzle and filled into the flow path of each ion-selective electrode, and the reference electrode solution is introduced into the flow path of the comparison electrode 104 from the reference electrode solution bottle 161 ( S304).

The electromotive force of each electrode is measured by the potential measurement unit 171 immediately after the sample is introduced into the electrode flow path and while the liquid is stationary (S305). In addition, the liquid remaining in the dilution tank is sucked up using a vacuum suction nozzle.

Next, the concentration calculation unit 172 extracts the potential value for concentration calculation from the potential measurement unit 171 (S306), and uses the following equations (4) and (5) from the above slope sensitivity and internal standard solution concentration. The concentration of the specimen is calculated (S308).
(C) Concentration of specimen C _S = C _IS ×10 ^b ... Formula (4)
b=(EMF _IS -EMF _S )/SL...Equation (5)

However, _CS : Sample concentration EMF _S : Measured electromotive force of sample

This example device corrects the calculation of the sample measurement based on the measured potential value of the internal standard solution with a constant concentration, which is measured before sample measurement. Even if fluctuations (potential drift phenomenon) occur, accurate measurements can be achieved. Note that the measured potential of the internal standard solution may be used not only before the sample measurement but also before and after the sample measurement.

Separately, the interfering ion analysis unit 181 extracts a potential waveform for interfering ion analysis from the potential measurement unit 171 (S321).

Furthermore, the interfering ion analysis unit 181 extracts the potential waveform for temperature analysis from the potential measurement unit 171 (S331), and uses the result of calculating the temperature influence (S332) to generate the potential waveform for interfering ion analysis extracted in S321. The influence of temperature on is corrected (S322), and the influence of interfering ions is calculated (S323). In this way, the interfering ion analysis unit 181 detects the influence of interfering ions based on the potential change over time obtained from the ion-selective electrode while the liquid of the sample is still after the sample comes into contact with the ion-selective electrode. do.

Then, the interfering ion analysis unit 181 displays the interfering ion influence detection result together with the measurement target ion concentration result on the output unit 174 (S309). In particular, the output unit 174 displays the detection results of the influence of interfering ions. This allows the user to know the influence of interfering ions.

If the next specimen is to be measured, the process returns to S302; if not, the measurement ends (S311) (S310).

In addition, in the apparatus of this embodiment, in S321 and S331, the potential waveform not only when measuring the specimen but also when measuring the internal standard solution is extracted, and the waveform is used to confirm changes in the apparatus state.

Here, a method for calculating the influence of interfering ions will be described. FIG. 4 shows the potential waveform of the entire time domain in one cycle during sample liquid measurement in this example. The time domain is mainly divided into (a) when the sample liquid is introduced, (b) when the liquid is stationary, (c) when the reference electrode liquid is introduced, and (d) when the liquid is stationary.

When introducing (a) a sample liquid or (c) introducing a reference electrode liquid, vibrations, liquid flow, and electrical noise are generated due to the operation of the solenoid valve, pinch valve, syringe pump, etc., and therefore the potential waveform is disturbed. As the potential waveform (S321) for interfering ion analysis in this example, the time domain when the liquid is stationary in (b) and (d) is extracted. Note that the potential waveform does not need to be a continuous waveform or a waveform that includes values at many times, but only needs to include potential values at two or more different times when the liquid is stationary.

The potential waveform obtained in S321 is subjected to temperature influence correction, which will be described later. The storage unit 182 stores the correlation between the potential waveform and the interfering ions in the time domain, and by analyzing the temperature-corrected potential waveform using the information in the storage unit, the influence of the interfering ions can be eliminated. It can be calculated.

The storage unit 182 stores the relationship of potential changes over time with respect to interfering ions. For example, the interfering ion analysis unit 181 identifies the type of interfering ion based on the direction of change in the potential waveform. As a specific example, if the temporal slope of the potential waveform is positive, it is determined that lipophilic interfering ions such as Br ^- and SCN ^- are included. If the temporal slope is negative, it is determined that hydrophilic interfering ions such as HCO ₃ ^- are included. In this way, the type of interfering ion can be identified.

Furthermore, by comparing the information stored in the storage unit 182, the type or concentration of interfering ions can be estimated from the magnitude of the slope. Further, when the type of interfering ion is known, the interfering ion analysis unit 181 calculates the concentration of interfering ions according to the magnitude of the slope based on the slope of the change in the potential waveform. In this way, the concentration of interfering ions can be calculated.

Note that the information stored in the storage unit 182 may be inputted before the device is shipped, but it is preferable that the user input the information using the input unit 176 according to the condition of the device used and the characteristics of the electrodes. I can do it.

For example, the input unit 176 may be used to input information regarding the specimen into the storage unit 182. The information regarding the sample may represent, for example, the type of drug that may be contained in the sample, and the storage unit 182 stores the type of drug and the type of interfering ion contained in the drug in association with each other. You may do so. In this way, the type of interfering ion is specified by inputting the type of drug, so the concentration of interfering ion can be estimated more accurately.

Here, the hydrophilicity and lipophilicity of ions will be explained. The minimum concentration required to salt out proteins varies depending on the ion species, and the permutation is known as the Hofmeister series. Regarding anions,
SO ₄ ^- >HCO ₃ ^- >Cl ^- >Br ^- >NO ₃ ^- >I ^- >SCN ^-
The left side is called a hydrophilic ion and the right side is called a lipophilic ion. Generally, the ion selectivity of a Cl ion electrode tends to increase in the reverse order of the Hofmeister series. That is, it tends to respond more easily to Br ^{- ,} which is more lipophilic than Cl -, and less responsive to HCO ₃ ^- , which is more hydrophilic than Cl ^- .

Here, a measurement example in this example is shown in FIG. These are potential waveforms obtained when several aqueous solutions with different compositions were prepared and measured as simulated specimens. The compositions of the aqueous solutions are as follows.
(a) Cl ^- 100mM
(b) Cl ^- 100mM + _HCO3 ^- 40mM
(c) Cl ^- 100mM + _HCO3 ^- 140mM
(d) Cl ^- 100mM + HCO ₃ ^- 40mM + Br ^- 20mM
(e) Cl ^- 100mM + HCO ₃ ^- 40mM + SCN ^- 10mM
It is. The vertical axis is potential and the horizontal axis is time. The time area surrounded by the thick dotted line is the area where the potential is not stable due to the operation of the drive mechanism, and the other area is the time when each liquid is introduced into the electrode flow path and the liquid is stationary. It is an area.

As mentioned above, all the samples measured here have the same Cl ion concentration. The influence of interfering ions differs depending on the selectivity of each ion in the electrode, and while it has relatively little effect on the hydrophilic ion HCO ₃ ^- , it does have an effect on lipophilic ions such as Br ^- even at low concentrations. I can see that it has been greatly received.

If, for example, the potential for concentration calculation is acquired at a time point of 6000 ms when the potential is relatively stable as in the conventional device, different values will be obtained. When the concentration is calculated from this potential, when interfering ions are included, a concentration different from the true value is output as the Cl ion concentration, but it is not possible to determine whether or not interfering ions are included. For this reason, conventional devices avoid analyzing samples in which the state of interfering ions in the blood has changed, such as during medication. In contrast, in this embodiment, it is possible to simultaneously output whether or not the calculated Cl ion concentration value has been affected by interfering ions, thereby informing the user.

This method will be explained. FIG. 5 shows a dashed-dotted line extending horizontally from the potential value at 2000 ms of each specimen. The deviation from these dashed-dotted lines represents potential changes over time.

Looking at the potential at 6000 ms, (a) shows almost no deviation from the dashed-dotted line, (b) has a slightly lower value compared to the dashed-dotted line, and (c) shows a significant difference from the dashed-dotted line. The value was low. On the other hand, values (d) and (e) were higher than the dashed line.

The reason for this is as follows. (a) contains only Cl ^- and no interfering ions, so the potential does not change over time while the liquid is stationary, whereas (b) contains 40mM of HCO ₃ ^- , a hydrophilic ion. (c) had a larger negative slope because it contained 140 mM of HCO ₃ ^- . On the other hand, (d) and (e) showed a positive slope because not only HCO ₃ ⁻ 40 mM but also lipophilic ions Br ⁻ and SCN ⁻ were included.

The storage unit 182 stores information regarding the correlation between ion species, concentration, and potential, and the interfering ion analysis unit 181 analyzes the obtained potential waveform and determines a value with this amount of deviation. If it exceeds the limit, the output section outputs information about the influence of interfering ions.

For example, since serum usually contains 30 to 40 mM HCO ₃ ⁻ , a slope similar to that of the curve (b) can be used as a reference. Based on (b), a sample with a slope like that in (b) is normal, and a sample with a flat waveform in (a) is output with a possibility that HCO ₃ ^- is significantly lower than normal. However, for a sample with a negative slope waveform like (c), it outputs the possibility that the sample contains more hydrophilic ions than usual, and a sample with a positive slope like (b) and (e) For samples with a waveform of , the possibility that lipophilic ions are included is output. By looking at these results, the user can examine the identity of the sample and at the same time judge the reliability of the output Cl ion concentration analysis value.

The reason why the potential changes over time when measuring a sample containing interfering ions will be explained using the schematic diagram of FIG. 6.

611 and 621 indicate ion-sensitive membranes, and 612 and 622 indicate sample solutions. 610 shows the state immediately after the sample liquid is introduced, and 620 shows the state after the liquid has stopped.

The Cl ion sensitive membrane of this example is based on an ion exchange membrane, and the sensitive membrane 611 contains immobilized cations at a high concentration and Cl ^{2 -} as a counter anion at a high concentration. Therefore, when it comes into contact with a sample liquid containing interfering ions J ^- , ion exchange between interfering ions J ^- in the sample liquid and Cl ^- in the membrane occurs quickly. This is a phenomenon that characteristically occurs when a membrane having a high density of fixed charges is used as an ion-sensitive membrane.

For example, when a sample solution containing HCO ₃ ^- is introduced, that is, when J ^- is HCO ₃ ^- , immediately after the introduction, HCO ₃ ^- in the sample solution and Cl ^- in the membrane are exchanged, and the liquid remains stationary. In the case of 100%, J ^- ions in the sample liquid near the membrane are replaced by Cl ^- ions.

The Cl ion electrode has higher selectivity for Cl ⁻ than HCO ₃ ⁻ and is easier to respond to, so when HCO ₃ ⁻ in the sample liquid near the membrane surface is exchanged for Cl ⁻ , the Cl ion electrode I feel that the ion concentration of the sample solution has increased. Since the slope sensitivity is negative, the potential changes in a downward direction as the exchange reaction of J ^- in the sample solution to Cl ^- progresses. When the same sample liquid is reintroduced, the sample liquid is refreshed and the same phenomenon occurs again.

Although HCO ₃ ⁻ also flows into the membrane side, since Cl ⁻ exists in the membrane at a high density, the influence on the membrane side is small.

Furthermore, when a sample solution containing Br ^- or SCN ^- is introduced, that is, when J ^- is Br ^- or SCN ^- , ion exchange occurs between the sample solution and the membrane, but the Cl ion electrode Since the selectivity for Br ^{- and} SCN ^- is higher than for Cl -, when Br ^- and SCN ^- in the sample liquid near the membrane surface are exchanged with Cl ^- , the Cl ion electrode uses ions in the sample liquid. I feel that the concentration has decreased. Since the slope sensitivity is negative, the potential changes in the upward direction.

In order to understand this phenomenon more easily, we will discuss the results of verifying the principle using a simple experimental system. A block diagram of the experimental equipment is shown in Figure 7. A Cl ion electrode 701 is provided in the left channel, and a comparison electrode 702 is provided in the right channel via a droplet. From the right, the comparison electrode solution can be introduced into the comparison electrode flow path using a syringe 712 filled with the comparison electrode solution. From the left, a sample liquid can be introduced into the Cl ion electrode channel using a sample liquid syringe 711.

An operation was carried out in which the solution was introduced, the solution was allowed to stand still for about 3 minutes, and then the next sample solution was introduced, and the solution was allowed to stand still for another 3 minutes. During the series of measurements, the potential between the Cl ion electrode channel and the reference electrode was continuously measured.

The potential measurement results in this experiment are shown in FIG. The vertical axis shows potential and the horizontal axis shows time. (1) to (3) for NaCl aqueous solutions with different concentrations, all of them show stable potential over time, but (4) for a 10mM _NaHCO3 aqueous solution, the potential suddenly changes immediately after the solution is stationary. There was a tendency for the change to gradually become gradual. (4') When an aqueous NaHCO ₃ solution with the same concentration was introduced again, the potential started from almost the same as in (4) and a similar curve was drawn. (5) When a 100 mM NaHCO ₃ aqueous solution was introduced, the potential similarly changed in the negative direction. On the other hand, (6) when a 10mM NaBr aqueous solution was introduced, there was a tendency for the potential to rise rapidly immediately after the solution came to rest, and the change gradually become gentler, contrary to the case of the NaHCO ₃ aqueous solution. (7) A 10mM NaSCN aqueous solution showed a more significant potential change. (7') The phenomenon was reproduced when 10 mM NaSCN aqueous solution was reintroduced. Finally, when a 10 mM NaCl aqueous solution was introduced into (2') and (2''), almost the same potential as in (2) was exhibited. As described above, results supporting the phenomenon explained using FIG. 6 were obtained.

Generally, in an ion-selective electrode, it is considered that it is better not to generate ion flux from the ion-sensitive membrane, since this leads to deterioration of the lower limit of measurement concentration. However, in this embodiment, this phenomenon is used in reverse to make it possible to detect not only the concentration of ions to be measured but also interfering ions with one electrode.

The situation in which the above phenomenon occurs will be explained using the schematic diagram of FIG. 9. It is thought that the following two different phenomena occur mainly depending on the magnitude relationship between the diffusion rate in the membrane and in the liquid and the ion exchange reaction rate. These are shown at 910 and 920 in FIG.

910 and 920 schematically show changes in the concentration of interfering ions in each domain in the case of diffusion control in the membrane and the case of diffusion control in the boundary layer, respectively. The ion selective electrode has an internal solution (Inner Filling Solution; IFS), and the internal solution contains ions to be measured at a high concentration. High concentration here means an ion concentration higher than that contained in the sample liquid to be measured.

In 910 and 920 of FIG. 9, the area between the two thick vertical solid lines indicates the ion-sensitive membrane (the "membrane"), the left side of the membrane indicates the sample liquid (the "sample"), and the right side of the membrane indicates the interior. (“IFS”).

The regions of the sample liquid and the internal liquid near the membrane, that is, the regions closer to the membrane than the vertical broken line, are their respective boundary layers, that is, the regions where no liquid flow occurs and only diffusion occurs predominantly.

When the ion diffusion within the membrane is sufficiently slow compared to the ion diffusion in the boundary layer in the liquid, the distribution of interfering ion concentration becomes intra-membrane diffusion rate-limiting 910. That is, when a sample solution containing interfering ions comes into contact with the membrane, ions are exchanged with the ions in the membrane. Because diffusion within the membrane is slow, ions on the membrane surface are first replaced by interfering ions. The ratio varies depending on selectivity and other factors. Diffusion in the sample liquid is sufficiently faster than in the membrane, so there is little change in the ion concentration in the boundary layer. This model can be applied to electrodes that include a so-called liquid film type ion-sensitive membrane made of soft polyvinyl chloride with a quaternary ammonium salt added, because the fixed charge density is low and ion diffusion within the membrane is slow.

On the other hand, it gradually diffuses in the film, and the concentration gradient changes in the order of x1, x2, x3, and x4 as shown by the arrow. When interfering ions reach the internal fluid, ion exchange occurs between the internal fluid and the membrane. Since the internal liquid contains sufficient Cl ions and also diffuses sufficiently quickly compared to the inside of the membrane, the ionic composition of the boundary layer of the internal liquid hardly changes. After a certain period of time, it reaches an equilibrium state. Note that it takes a long time to reach an equilibrium state.

On the other hand, if the ion exchange reaction is sufficiently faster than the ion diffusion within the boundary layer, diffusion within the boundary membrane becomes rate-limiting 920. When a sample solution containing interfering ions comes into contact with the membrane, ions are exchanged with the ions in the membrane. Since the ion exchange capacity of the membrane is large and the interfering ions taken into the membrane surface diffuse through the membrane, the interfering ion concentration on the membrane surface hardly increases.

On the other hand, since ion diffusion within the boundary layer of the sample liquid is slower than in the ion exchange reaction, the supply of interfering ions from the bulk layer of the sample cannot keep up, and the concentration of interfering ions in the boundary layer of the sample liquid near the membrane increases. As shown in , it gradually decreases in the order of y1, y2, y3, and y4. In this way, the composition ratio of ions in the sample liquid near the membrane surface changes until an equilibrium state is reached. In this example, it is considered that the phenomenon occurring due to rate-limiting diffusion within the boundary layer shown at 920 is captured. Note that FIG. 9 described above is an image diagram schematically showing the direction of concentration change in each domain, and it is considered that the profile is not actually a linear profile.

However, even if the rate of diffusion in the boundary membrane is limited by 920, if the ion exchange reaction of the membrane is too rapid for the concentration of interfering ions in the sample liquid, the interfering ions in the boundary layer of the sample liquid will be depleted instantaneously. In some cases, it may be difficult to capture changes over time. Conversely, if the ion exchange reaction of the membrane is too slow relative to the concentration of interfering ions in the sample solution, the change may be small and difficult to detect. Therefore, this embodiment can be easily applied by selecting a sensitive membrane having an appropriate ion exchange rate depending on the ion concentration region to be detected and the time scale measured by the device.

Suitable conditions for utilizing the principle of this example are: (1) the device is capable of acquiring the potential of the sample liquid immediately after introduction and while the liquid is stationary in an appropriate time range; (2) ions of the electrode The sensitive membrane must have a high-density fixed charge, (3) the internal solution must contain a high concentration of ions to be measured, and (4) operations must be performed periodically to maintain the ion balance within the membrane (e.g. , the liquid containing the ions to be measured is periodically measured by an operation such as periodically flowing a liquid containing the main ions, etc., as shown in FIG. 3).

This example satisfies all of (1) to (4) above, and an ion-exchange membrane-based ion-sensitive membrane is more suitable for automatic analyzers that need to measure biological samples such as serum with high throughput. It's a choice.

Note that the standard for "high concentration" in (3) can be appropriately determined by a person skilled in the art, but for example, it may be the upper limit of the concentration range of the ion to be measured that is assumed to be normally contained in the sample, or a value higher than this. The value may be the upper limit of the concentration range of target ions that can be measured by the concentration measuring device 100 or a value higher than this.

Ion exchange membranes have a high ion exchange capacity, so they are sometimes academically referred to as high-capacity ion-exchangers. This high exchange capacity is achieved because a membrane with a high density of fixed charges is used. On the other hand, in the case of a Cl ion-sensitive membrane having a different membrane structure, such as a general soft polyvinyl chloride membrane containing a quaternary ammonium salt, it does not have such a high density of fixed charges. As described above, those skilled in the art can clearly determine whether or not a film having a high density of fixed charges is used as a sensitive film based on the type of film and the like.

Here, a method for temperature correction of the potential waveform will be described. Even when sample liquids at different temperatures are introduced into the ion-sensitive membrane and the liquids come to rest, a temporal gradient in the potential waveform occurs depending on the direction and degree of the temperature difference. This temperature difference affects not only the potential of the Cl ion electrode but also the potential of the Na and K ion electrodes.

The direction of the potential change over time is reversed depending on the sign of the charge of the ion to be measured and the direction of the temperature difference, and the degree of influence changes depending on the thickness of the sensitive membrane and the like. In this example, when the temperature of the sample liquid is lower than the temperature of the electrode, the potential of the Cl ion electrode when the liquid is stationary has a positive slope over time, and the potential of the Na, K ion electrodes has a negative slope. . When the sample liquid temperature is higher than the electrode temperature, the opposite tendency occurs.

Furthermore, since the film of the Na, K ion electrode in this example is thicker than the film of the Cl ion electrode, the potential gradient is larger by a certain percentage than that of the Cl ion electrode. Information on the correlation regarding the characteristics of the Na, K, and Cl ion electrodes with respect to changes in potential due to the influence of temperature differences is stored in the storage unit 182.

In S331 of FIG. 3, the interfering ion analysis unit 181 extracts the potential waveform of the Na, K ion electrodes while the liquid is still, measured by the potential measurement unit 171, as a potential waveform for temperature analysis. From the extracted potential waveform, the degree of influence of the temperature difference in the measurement (for example, the slope of the potential change over time) is calculated (S332).

Using the correlation of the characteristics of each electrode with respect to the temperature difference stored in the storage unit 182, the temperature influence is corrected from the potential waveform for interfering ion analysis (S322). For example, a different coefficient is stored for each ion-selective electrode, and the slope of the potential change over time is multiplied by this coefficient. To give a more specific example, changes in potential are insensitive to temperature when the film is thin, and sensitive to temperature when the film is thick, so it is possible to store a coefficient depending on the thickness of the film.

In this manner, the interfering ion analysis unit 181 compares the potential waveform of the ion-selective electrode that responds to the ion to be measured and the potential waveform of the electrode that responds to an ion with a different sign from the ion to be measured. Since Na and K ion electrodes are not susceptible to interference from anions and are less susceptible to interference from cations, by calculating the temperature effect from the potential waveform of the Na and K ion electrodes, we can calculate the temperature effect on the potential waveform of the Cl ion electrode. can be appropriately corrected.

With an electrolyte analyzer used in this example for analyzing biological samples, the identity of the specimen to be measured is often known to some extent in advance, so by inputting this information in advance, it is possible to eliminate interfering ions. It is possible to improve the accuracy of impact detection.

For example, serum typically contains 30 to 40 mM HCO ₃ ^- . When calibration is performed in a state that contains HCO ₃ ⁻ for serum analysis at the time of calibration, in the conventional apparatus, when a control serum that does not contain HCO ₃ ⁻ is analyzed, the Cl concentration becomes a low value. However, in this example, by inputting the sample information of serum in advance, if the potential waveform does not have a negative slope, a sample that does not contain HCO ₃ ^- , such as a freeze-dried sample of controlled serum, can be detected. It can be detected that there is a possibility that it has been measured.

In this example, the sequence is such that it is difficult to obtain the potential waveform while the liquid is stationary after introducing the sample liquid, but if the sequence is to introduce the reference electrode solution first and then introduce the sample, the sample liquid Analysis becomes easier because the potential waveform immediately after introduction can be acquired with less disturbance.

Further, it is also possible to make the flow path configuration, the structure of the reference electrode, etc. different from those in this example. Furthermore, the analysis method may be different from that of this embodiment, as long as the magnitude and direction of the difference can be determined from the potentials at two or more points at different times while the liquid is still.

Further, temperature correction is not necessarily necessary, and it is not necessary to use the waveform of the internal standard solution as a reference. If the above-mentioned conditions are satisfied, the influence of interfering ions can be detected in the same way with anion electrodes and cation electrodes other than the Cl ion electrode. Note that when detecting the influence of interfering ions on the cation electrode, it is preferable to devise the above-mentioned temperature correction method. On the other hand, as mentioned above, it is more difficult to fabricate a highly selective sensitive membrane with an anion electrode, so it is more useful to apply it to an anion electrode, which is more susceptible to the effects of interfering ions.

As explained above, the electrolyte concentration measuring device according to this embodiment can more easily determine the type or concentration of interfering ions. Also, one electrode can make such a determination.

[Example 2]
The electrolyte concentration measuring device according to Example 2 differs from Example 1 in that the result of analyzing the influence of interfering ions is reflected in the Cl ion concentration calculation, and the Cl ion concentration is calculated with the influence of interfering ions corrected. The device configuration and calibration method are the same as in the first embodiment.

Here, FIG. 10 shows the flow during continuous analysis in the apparatus of this embodiment. The difference from the flow of Example 1 is that the influence of interfering ions is calculated by fitting a function stored in the storage unit 182 to the obtained potential waveform (S324), and the result is used to calculate the potential for concentration calculation. (S307). This makes it possible to calculate the Cl ion concentration without the influence of interfering ions.

In the calculation in this embodiment, S324, S307, and S308 are executed simultaneously. Specifically, the storage unit 182 stores a function F _j (C j , t) having concentration (C _j ) and time (t) as variables as a potential time change model for each interfering ion ( _j ). Stored. By fitting the potential waveform obtained in S306 to the potential waveform for interfering ion analysis, the Cl ion concentration (C _Cl ) and each interfering ion concentration (C _j ) are determined. Expressed as a formula, it becomes the following formula (6).
E(t)=G(C _Cl )+Σ _j [F _j (C _j , t)] ... Formula (6)

E(t) represents the measured potential waveform, and G(C _Cl ) represents the potential value at a certain Cl ion concentration using a function having the concentration (C _Cl ) as a variable. Since this does not change over time, the variable at time t is not included. Note that these functions improve analysis accuracy by reflecting information such as the slope sensitivity, selectivity, and ion exchange rate of the electrodes actually used, so the user may input these information into the storage unit 182. It may be determined in advance by measurement. Input unit 176 may be used to input characteristics of the ion-selective electrode (for example, G(C _Cl ) and/or function F _j (C _j ,t)) into storage unit 182 .

In this way, the concentration calculation section 172 corrects the influence detected by the interfering ion analysis section 181 and calculates the concentration of the ion to be measured.

Note that Cl ion electrodes have different selectivity, partition coefficient, ion exchange reaction rate, and diffusion rate depending on the interfering ion species and concentration in the sample solution, so analysis can be performed using the fact that each shows a different potential waveform. are doing. On the other hand, certain combinations of ion species and concentrations may result in similar waveforms. In that case, it becomes difficult to calculate the type and concentration of interfering ions.

However, with an electrolyte analyzer like the one in this example, the identity of the sample to be measured is often known to some extent in advance, so by inputting this information in advance, it is possible to calculate the concentration of Cl ions and interfering ions. It is possible to improve the accuracy of

For example, since serum generally contains 30 to 40mM HCO ₃ ^- , in this example, if the specimen information that the specimen is serum is input in advance, the potential waveform usually has a negative slope. Therefore, analysis such as fitting with priority given to the HCO ₃ ⁻ function becomes possible.

Furthermore, due to drug inoculation, etc., the sample may contain interfering ions such as Br ^- , which are not normally contained in blood. In such cases, by inputting the patient's medication information into the device in advance as information regarding the sample, it is possible to perform waveform analysis with priority given to fitting the function of the interfering ion species depending on the drug. Accuracy can be improved. The information regarding the sample may represent, for example, the type of drug that may be contained in the sample, and the storage unit 182 stores the type of drug and the type of interfering ion contained in the drug in association with each other. You may do so.

In this way, the type of interfering ion is specified by inputting the type of drug, so the concentration of interfering ion can be estimated more accurately. In addition, it is possible to calculate not only the Cl ion concentration but also the concentration of interfering ions caused by drug administration, which may be used as an index of pharmacokinetics.

Note that the input unit 176 and output unit 174 of this embodiment can be used by the user to directly input information or directly view output, but they can also be used for electronic medical records, medication information, device integrated monitoring systems, etc. It can also be linked with other information systems.

As described above, the electrolyte concentration measuring device according to the present example can more easily determine the type or concentration of interfering ions, similarly to Example 1. Also, one electrode can make such a determination.

[Example 3]
The configuration of the electrolyte concentration measuring device according to Example 3 differs from Example 1 in that, in addition to the Na, K, and Cl ion electrodes, it is equipped with an anion electrode that has different characteristics from the Cl ion electrode. be. The anion electrode to be added has some or all of the characteristics of ion selectivity, ion exchange reaction rate, ion diffusion coefficient in the sensitive membrane, fixed charge density, type of internal liquid, and type of main ion compared to other anions. Different from ion electrodes. In this way, the electrolyte concentration measuring device according to this example is equipped with N ion-selective electrodes having different characteristics.

The number of additional electrodes to be installed varies depending on the number of ion species to be analyzed. In this example, the number of anion electrodes including the Cl ion electrode is N. That is, when a certain sample liquid is measured, N potential waveforms that differ depending on the ion species and concentration contained in the sample liquid and the electrode characteristics are obtained.

Here, FIG. 11 shows the flow during continuous analysis in this example. Main points that are different from FIG. 10, which is the flow of the second embodiment, will be described.

Regarding the Na and K ion concentrations, the concentrations are calculated from the potentials at stable timing as in Figure 10, but regarding the anion concentrations, N potential waveforms obtained from N anion electrodes when the liquid is stationary are calculated. It is extracted (S341). As in the second embodiment, temperature influence correction is performed on these waveforms (S342).

After that, the potential waveform of each electrode is fitted using the time-related functions of the anion species and concentration of each electrode stored in the memory, and all fitting results are integrated and analyzed. The type and concentration of ions are calculated (S343).

By using this method, it is also possible to determine the concentration of N or more ions from the potential waveforms generated by N ion-selective electrodes. Furthermore, it is also possible to measure the ion concentrations of N+1 or more ion species based on the potential waveforms over time obtained from the N ion-selective electrodes. A person skilled in the art can appropriately design a specific method for calculating N+1 values based on N waveforms based on known techniques. Note that the analysis method used in S343 is not particularly limited, and machine learning, neural networks, or the like may be used.

As described above, the electrolyte concentration measuring device according to the present example, like Examples 1 and 2, can more easily determine the type or concentration of interfering ions.

The present invention is not limited to the above embodiments, but includes various modifications. For example, the embodiments described above are described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add, delete, or replace a part of the configuration of each embodiment with other configurations.

100...Electrolyte concentration measuring device (electrolyte analyzer)
101...Cl ion electrode (ion selective electrode)
102...K ion electrode (ion selective electrode)
103...Na ion electrode (ion selective electrode)
104... Reference electrode 105... Pinch valve 106... Vacuum suction nozzle 107... Sipper nozzle 108... Diluent supply nozzle 109... Internal standard solution supply nozzle 110... Dilution tank 111... Waste liquid tank 112... Vacuum pump 120... Liquid junction section 121-127 ...Solenoid valve 131...Syringe pump for internal standard solution 132...Syringe pump for diluted solution 133...Sipper syringe 141...Internal standard solution bottle 151...Diluted solution bottle 161...Reference electrode solution bottle 170...Measuring section 171...Potential measuring section 172... Concentration calculation section 174... Output section 175... Device control section 176... Input section 181... Interfering ion analysis section 182... Storage section 611... Sensitive membrane 701... Cl ion electrode (ion selective electrode)
702... Reference electrode 711... Syringe for sample liquid 712... Syringe 910... Diffusion rate-limiting in the membrane 920... Diffusion rate-limiting in the boundary membrane

Claims (15)

In an electrolyte analyzer that has an ion-selective electrode and uses potential measurement,
It has a memory section that stores the relationship of potential changes over time with respect to interfering ions,
After the sample comes into contact with the ion-selective electrode, the sample includes an interfering ion analysis unit that detects the influence of the interfering ions based on a potential change over time obtained from the ion-selective electrode while the sample is still. An electrolyte analyzer characterized by: The electrolyte analyzer according to claim 1, wherein the interfering ion analysis section identifies the type of the interfering ion based on the direction of change in potential waveform. The electrolyte analyzer according to claim 1, wherein the interfering ion analysis section calculates the concentration of the interfering ions based on a slope of a change in a potential waveform. The electrolyte analyzer has a concentration calculation unit that calculates the concentration of the ion to be measured,
The electrolyte analyzer according to claim 1, wherein the concentration calculation section calculates the concentration of the measurement target ion by correcting the influence based on the influence detected by the interfering ion analysis section. The electrolyte analyzer according to claim 1, wherein the ions to be measured are anions. The interfering ion analysis section includes:
a potential waveform of the ion-selective electrode;
The potential waveform of the electrode that responds to ions with a different sign from the ions to be measured,
The electrolyte analyzer according to claim 1, characterized in that the electrolyte analyzer compares. The electrolyte analyzer according to claim 1, wherein the ion-selective electrode is a flow-type ion-selective electrode. 2. The electrolyte analyzer according to claim 1, wherein a membrane having a high density of fixed charges is used as the sensitive membrane of the ion-selective electrode. The electrolyte analyzer according to claim 1, wherein the sensitive membrane of the ion-selective electrode includes an ion exchange membrane. The electrolyte analyzer according to claim 1, wherein the ion-selective electrode has an internal liquid, and the internal liquid contains ions to be measured at a high concentration. 2. The electrolyte analyzer according to claim 1, wherein the electrolyte analyzer periodically measures a liquid containing ions to be measured. The electrolyte analyzer according to claim 1, further comprising an output section that displays the detection result of the influence of the interfering ions. The electrolyte analyzer according to claim 1, further comprising an input section used to input characteristics of the ion-selective electrode into the storage section. The electrolyte analyzer according to claim 1, further comprising an input section used to input information regarding the specimen into the storage section. Equipped with N ion-selective electrodes having different characteristics,
2. The electrolyte analyzer according to claim 1, wherein the ion concentration of N+1 or more ion species is measured based on a potential waveform over time obtained from each of the ion-selective electrodes.

Images